As someone who is also looking into getting a wii modchip, and am looking at the same chips you are, I'll just summarize what I've learned thus far.

Most everyone has said that installing the mod chip is not that hard for even n00bs like myself. There are some video tutorials you can watch. Then, you can practice soldering wires onto old remote control pcbs and stuff like that before you go at installing the mod chip. I may have a professional install it for me or have a more experienced friend help me or something.

The WiiKey looks alright, except that it has problems with Dual Layer DVD Originals, and an update has yet to be released. Since the site (wiikey.cn) doesn't appear to be around anymore, I think the WiiKey developments could be dead, but I could be wrong.

It doesn't look like you actually have to make the YAOSM chip. All you have to do is buy the chip for it. You would just have to build the programmer for it, which everyone has also told me doesn't take very long to do, nor is it very hard. To solder the chip you could just stick it in a socket and solder the socket to the Wii. DVD updating is supposed to be out with YAOSM v3, but I don't know when that will be coming around.

And yup, the WiiKey does not work with Original DL DVD games, so an original copy of SSB: Brawl would be a no go, which could be a problem in the future if we end up needing originals to get online.